In recent years, optical wireless communication modules represented by infrared data association (IrDA) and the like, optical sensor modules, and the like have been widely mounted in electronic devices such as a mobile phone and a notebook personal computer. For example, PTL 1 discloses an optical proximity sensor (reflection type optical coupling device) that is mounted in a mobile phone.
Such a portable electronic device has a battery as an electric power source. Thus, it is highly desirable to reduce the electric power consumption of mounted modules. In an optical wireless communication facility that uses illumination, it is also desirable to reduce electric power consumption from the viewpoint of energy efficiency. In the optical wireless communication modules, the optical sensor modules, and the like, a light source that emits light mainly consumes electric power. Thus, it is desirable to reduce the electric power consumption of the light source.
Safety of eyes of a person (eye safety) should be secured for a light source that is used for optical wireless communication, optical sensing, and the like. In addition, since such a light source is used for optical wireless communication, optical sensing, and the like, the light distribution properties of the light source need to be regulated.
For example, PTL 2 to PTL 4 disclose an eye-safe light source in which laser light emitted by a semiconductor laser is made eye-safe. In the eye-safe light source disclosed in PTL 2 to PTL 4, transmitting the laser light through a light scattering layer increases the spot diameter of the laser light, and the laser light is made eye-safe. PTL 5 discloses the shape of a lens that regulates light distribution characteristics such that light from an eye-safe light source in which laser light is made eye-safe is regulated to have a light intensity distribution suitable for optical wireless communication.